Samsung Galaxy S4 — Lollipop Lock Screen temperature-unit problem

My S4 was updated to Lollipop 5.0.1 last weekend and now the tiniest problem is giving me the greatest hassle:

The Lock Screen includes brief weather info (icon, temperature, town) but the temperature is shown in Fahrenheit whereas I always work in Centigrade. My only weather app is Met Office which still shows Centigrade.

So far I haven't discovered how to change the Lock Screen to Centigrade. Can you help?

I would be just as happy if the weather info was removed from the Lock Screen. How can I do that?